Van type vehicles for passengers and for cargo have been equipped with a sliding side door. Sliding doors are supported and guided by rollers that run in tracks. These sliding doors are generally on the side of the vehicle opposite to the vehicle operator's station. To open or close the sliding doors, it is necessary for the vehicle operator to leave the operator's station and either walk around the outside of the vehicle to the sliding door or to cross the inside of the vehicle to the sliding door. Crossing the inside of the vehicle is often difficult or impossible due to passengers or cargo inside the van.
A power system for opening and closing sliding doors on vehicles has long been considered desirable. Attempts to provide a power system for opening and closing sliding doors have had limited success. The systems have generally been complicated and expensive. Some systems have not controlled the position of the door at all times thereby allowing some undesirable free travel. Other systems have not allowed manual opening or closing of sliding doors when the power system is inoperable for some reason.
Opening and closing time requirements and door slamming have also been problems. Sliding doors which move rapidly have tended to slam shut. Acceleration and deceleration of sliding doors and the resulting forces imposed on the vehicle body and sliding door have also been problems. Doors which close gently have tended to move slow and take excessive time to open and close.